Wireless communication systems are being developed to support higher data rates in order to meet a continuously increasing demand for wireless data traffic. For example, for the sake of data rate increase, the wireless communication systems are under technology development to improve spectral efficiency on the basis of a communication technology such as Orthogonal Frequency Division Multiple Access (OFDMA), Multiple Input Multiple Output (MIMO) and the like.
Due to an increase in demand for smart phones and tablet Personal Computers (PCs) and an explosion of application programs requiring a large amount of traffic, there occurs a problem that the demand for data traffic is accelerating while it is difficult to meet the explosive demand for wireless data traffic with only spectral efficiency improvement technology.
As a method for overcoming the aforementioned problem, wireless communication systems using microwave bands are attracting attention.
In supporting wireless communication through microwave bands, there is a problem that a frequency characteristic of the microwave band causes an increase of a propagation loss such as a path loss, a reflection loss and the like. Thus, the wireless communication systems using the microwave bands have a problem that the propagation loss makes a reaching distance of a radio wave short, thus decreasing service coverage.
Thus, by alleviating the path loss of the radio wave using a beamforming technology and increasing a propagation distance of the radio wave, the wireless communication systems using the microwave bands can increase the service coverage.
When using the beamforming technology as above, the wireless communication system can maximize a beamforming gain to optimize a performance index such as a Signal to Noise Ratio (SNR). However, when using the beamforming technology, there is a limitation that, because of a decrease of multipath propagation, the wireless communication system cannot obtain a diversity gain.